Technical Abstract:
Early season cold tolerance in grain sorghum [Sorghum bicolor (L.) Moench] is a desirable trait for extending its production range and minimizing risks associated with early spring plantings. We have used laboratory-screening techniques that aid in the identification of chilling tolerance. Germination/emergence assays were used to determine G50 and emergence indices. The rate of starch degradation by amylases released during sorghum germination at low temperatures was also used as a relative measure of metabolic processes during germination. The chilling-induced synthesis and accumulation of anthocyanin was used as an indicator of a sorghum lines’ sensitivity to low temperatures (seedling vigor). Additional measures of seedling vigor included root dry weight, shoot dry weight, root lengths, and shoot lengths. Finally, the metabolic fitness assay was used to determine genetic diversity in low temperature limitations of well-watered sorghum lines. These screening tools in combination with, molecular genetic analyses and breeding efforts have helped us identify candidate germplasm for use in enhancing sorghum’s cold tolerance.